Centaurus A

[AstroJason]

Captured this shot of Centaurus A last night. I was up against the full moon and light pollution of Sydney Olympic Park. Taken using my 60D at 200mm. This is a stack of 120 x 60 second exposures. Flats, Darks and Bias' applied.

I had those huge black halos around the brightest stars in the image but I have been learning how to fix them up in photoshop. They aren't entirely corrected but still working on my processing skills.

[JZ]

Nice shot.
I'm new to this stacking caper. Haven't tried it myself as yet.
What causes the black halos, and how do you fix them?

[Larryp]

Nice result, Jason!

[AstroJason]

Cheers guys. I forgot to add that that was just a 70% crop of the original image. The data was too noisy at 100%.

Ross, I think the dark halos around the stars are due to me using a DSLR lens (which isn't really designed for shooting long exposures of stars at night). The halos are there right out of the camera even before I begin processing. That said they can also be caused by over processing images as well but I have the problem of having them there even before I begin processing :(

Below is a direct link to a powerpoint presentation which I used to remove the dark halos from around the stars using photoshop.

Remove Dark Halos (https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CE0QFjAD&url=http%3A%2F%2Fwww.starrywonders. com%2Fcannistradarkhaloremoval.ppt&ei=WE97UbvLJe6YiAe94oGgCQ&usg=AFQjCNH3-MCggIld6HkBT8zzN88-IGsS_A&sig2=XonGU0gRbXkyzqLjZeu2Fg&bvm=bv.45645796,d.aGc)

[JZ]

Hi Jason,

Thanks for the explanation and the powerpoint.
I have not noticed the halos in my shots (I've only done a few so far).
I'll have to go back and have a closer look.